The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Wellbore reamers are known in the field of oil well drilling operations, and are used to open wellbores to allow for smooth operation of a drilling string. For example, U.S. Pat. No. 8,607,900 to Smith discloses a bi-directional reamer. Similarly, European Patent Application No. EP1811124 by Bassal, et al. discloses a similar type of bidirectional reamer.
While they are useful tools, these types of reamers have maintenance requirements that can result in increased costs in drilling. Wear and tear on the cutters or the tool body can result in effective failure of the tool, which can then require pulling the drill string to replace the reamer. Some wear of the cutting bits on a reamer is expected, but the rate of wear can be exacerbated by the configuration of the tool. For example, the configuration of the blades on a reamer may direct drilling fluid away from, rather than over, the cutting elements, resulting in excessive wear due to heating. Thus, it is desirable to provide improved fluid flow over the cutting elements of a reaming tool by improving the placement and positioning of the cutting elements relative to a body of the reaming tool, and the angle at which the cutting elements of the reaming tool interact with the wellbore in a drilling operation.
Additionally, current reaming-while-drilling tools utilize flat cap tungsten carbide inserts as the primary cutting elements on the cylindrical outer diameter. It is desirable to provide an improved cutting element design and material formulation to provide such a tool with greater efficiency. Similarly, current reamer designs place the tungsten carbide cutting inserts in simple rows and columns, which does not provide uniform distribution of the carbide against the hole wall. It is desirable to provide a reamer that aligns the cutting inserts so that there is more uniform coverage of the blade width, for example by providing helical cutting blades, positioned in close proximity to one another. It is desirable to provide a reamer with an improved blade design, over currently used helical blades for purposes of improving fluid flow over the cutting inserts.
Current reamer designs also provide polycrystalline diamond cutting inserts (hereinafter, “PDC inserts”) along portions of the blades. However current designs fail to balance the load on these cutters. It is thus desirable to allow for the implementation of back rake and side rake with PDC cutting inserts in order to balance the extremely heavy and cumbersome burdens and forces placed on the cutter. Providing such back rake and side rake improves drilling efficiency by providing better force balancing and load work distribution of the cutters regardless of their position.
There is therefore a long-felt need to provide a reaming tool with increased efficiencies in cutting insert size, composition, placement, and design.